The invention relates to a method of controlling a torque transmission system, to a torque transmission system for carrying out the method of controlling, and to a method of monitoring torque transmission systems.
It is known from the vehicle industry that, when changing the transmission ratio of a gear between a driving machine and a gearbox unit, the required clutching processes can be assisted or automated by a control or regulating algorithm. This facilitates the servicing of the engine unit or gearbox, and the clutching operation can be carried out in an energy saving manner with careful treatment of the materials. Furthermore, the control of a torque transmission system which is mounted at the output side of an automatic gearbox can be helpful, for example, in undertaking or guaranteeing adjustment processes and protective functions in the case of, for example, cone pulley belt contact gearboxes.
WO 94/04852 discloses a method of controlling torque transmission systems in conjunction with an automatic gearbox. The torque transmission system comprises a load branching out with a torque converter which is mounted in parallel with a friction clutch.
In accordance with this method, a driving torque transmitted by an engine unit is broken up into a hydraulic part which is to be transmitted by the converter and a mechanical part which is to be transmitted by the friction clutch, such as a lockup clutch. A central computer unit determines or calculates, in dependency upon the relevant operating condition of the system, the torque which is to be transmitted each time by the friction clutch. The remaining torque to be transmitted by the hydraulic torque converter constitutes the difference between the applied torque and the torque transmitted by the friction clutch and corresponds directly to a slip between the input and output parts of the torque transmission system.
Such method of controlling can be resorted to only in conjunction with an automatic gearbox and a lockup clutch. However, the acceptability of automatic gearboxes is only minimal in many fields of use. Furthermore, a lockup clutch of such kind is cost-intensive and bulky.
An object of the invention is to provide a method of controlling which can be used practically universally, the regulating quality of which is high, and which exhibits a clearly improved load change behavior for torque transmission systems.
In addition, one should achieve cost advantages in comparison with conventional torque transmission systems. Furthermore, an object is to provide a torque transmission system which can be utilized for the practice of such controlling method.
The above objects are accomplished in that the clutch torque which can be transmitted from an input side to an output side of a torque transmission system with or without load distribution or branching out is utilized as a control value and such control value is calculated and/or determined in dependency upon an input or driving torque.
This amounts to a realization of a torque matching concept. The basic concept underlying the method of such kind resides in controlling the setting member primarily in such a way that the clutch torque which can be transmitted by the torque transmitting parts is mainly just above or just below the driving torque at the input side or drive side of the torque transmission system.
As a rule, a torque transmission system must be designed for the transmission of two to three times the maximum driving torque of a driving machine, such as an engine. However, the driving torque which is typical of the operation is but a fraction of the maximum driving torque. The torque matching renders it possible to establish only that force-locking engagement which is required between the torque transmitting parts in lieu of a quasi permanent excessive overpressure.
A further advantage resides in the provision of a controlling method. In contrast to a regulation, the feedback of condition values of the torque transmission system is not absolutely necessary. It serves merely for a possible enhancement of the control but is not required in order to establish the operation of the torque transmission system. The task of a torque transmission system of such kind is to transmit torque. Therefore, it is expedient to use the transmittable clutch torque as a control value.
An advantageous embodiment of the invention is characterized in that, in a method of controlling a torque transmission system with or without load distribution or branching out which controls the torque adapted to be transmitted from an input side to an output side of the torque transmission system, the latter comprises a sensor system for detecting the values to be measured and a central control or computer unit which is connected with the sensor system, the torque which can be transmitted by the torque transmitting system being controlled in such a way that the transmittable torque is calculated, adapted and controlled as a function of a driving torque, and deviations from an ideal state are compensated for long-term through corrections.
Furthermore, it can be of advantage to resort to a method which serves to control a torque transmission system, especially for motor vehicles, wherein the torque transmission system is installed in the power flow downstream of a driving machine and in the power flow upstream or downstream of a shiftable device, such as a gearbox, and controls the torque which can be transmitted from an input side to an output side of the torque transmission system, and the power transmission system includes a control or computer unit which is in signal connection with sensors and/or other electronic units, the torque which can be transmitted by the torque transmitting system being calculated as a function of a driving torque and being adaptively controlled, with deviations from an ideal condition compensated for long-term through corrections.
According to another embodiment, the control value can be triggered by means of a setting member supplied with a setting value which is functionally dependent upon the transmittable clutch torque, in such a way that the transmittable clutch torque lies within a predetermined tolerance range at a slip limit wherein this slip limit is reached when the effect of a torque being applied at the input side exceeds the clutch torque which can be transmitted by the torque transmitting parts.
The method according to such embodiment can be carried out particularly in such a way that the torque which can be transmitted by a torque transmission system, such as a friction clutch and/or a hydrodynamic torque converter with or without converter lockup clutch and/or a starter clutch for automatic gearboxes and/or a turning set clutch and/or a torque transfer system connected in front of or behind an infinitely adjustable gearbox, such as a cone pulley belt contact gearbox, can be controlled as a function of a driving torque so that in the case of systems with load distribution or load branching, such as a hydrodynamic torque converter with converter lockup clutch, the torque which can be transmitted by the clutch is determined in accordance with the torque equation
MKSoll=KME*MAN
and
MHydro=(1xe2x88x92KME)*MAN
wherein the two equations apply for KMExe2x89xa61 and
MKSoll=KME*MAN
and
MHydro=0
applies for KME greater than 1 with
KME=torque division factor
MKSoll=desired clutch torque
MAN=applied torque
MHydro=torque transmittable by the hydrodynamic torque converter
and a torque difference between the torque MAN applied to the torque transmission system by the driving aggregate and the torque MKSoll transmittable by the clutch is transmitted through the hydrodynamic torque converter wherein a minimum slip is established independently between the engine and the output of the torque transmission system in dependency upon the torque division factor KME and deviations from the ideal condition are adoptively detected, processed and compensated for long-term.
A further embodiment of the method according to the invention proposes that the torque transmittable by the torque transmission system be controlled as a function of a driving torque so that in the case of systems without load distribution, such as a friction clutch and/or a starting clutch and/or a turning set clutch and/or a torque transmission system of an automatic gearbox or an infinitely adjustable gearbox, such as a cone pulley belt contact gearbox, the torque which can be transmitted by the friction clutch or starting clutch
MKSoll=KME*MAN
is ascertained and a definite overpressing of the torque transmitting parts is carried out for KMExe2x89xa71.
Furthermore, it can be advantageous if the torque which can be transmitted by a torque transmission system is varied as a function of a driving torque in such a way that in the case of systems without load distribution, such as a friction clutch and/or a starter clutch and/or a torque transfer system of an automatic gearbox and/or an infinitely adjustable cone pulley belt contact gearbox, the torque which can be transmitted by the torque transmission system
MKSoll=KME*MAN+MSicher
is ascertained and for KME less than 1 a fictitious load distribution is reconstructed through a supporting control loop to be a copy of the behavior of a parallel-connected torque transmission system, such as a hydrodynamic torque converter, and a proportion of the transmittable torque is transmitted through the torque control and the remaining torque is subsequently transmitted in dependency upon slip through a safety torque MSicher.
Furthermore, it can be advantageous if the safety torque MSicher is selected in dependency upon each operating point.
Similarly, it can be advantageous if the safety torque MSicher is ascertained and/or controlled in functional dependency upon the slip xcex94n or the throttle valve position d according to
MSicher=f(xcex94n, d).
Similarly, it can be expedient if the safety torque MSicher is ascertained and/or controlled in accordance with
MSicher=const.*xcex94n.
Furthermore, it can be advantageous if the torque division factor KME is constant within the entire operating range of the power train.
Similarly, it can be advantageous if the torque division or branching off factor KME assumes an individual value which is ascertained for each operating point and/or assumes at least in a portion of the operating range a relevant constant value each time; the values set in different portions of the operating range can be different.
In this manner, it is advantageously possible to divide the entire operating range into partial ranges wherein, in each partial range, the KME value is kept constant and the constant KME value can vary from operating range to operating range.
Furthermore, it may be advantageous if the value of the torque division factor KME is in functional relationship dependent upon the input RPM and/or the vehicle speed.
In accordance with the inventive concept, it can be advantageous if the value of the torque division factor KME is dependent exclusively upon the speed of the driving aggregate.
It can be equally advantageous if the value of the torque division factor is dependent, at least in a portion of the entire operating range, both upon the RPM and upon the input torque of the driving aggregate.
Furthermore, it may be advantageous if the value of the torque division factor KME is dependent not only upon the output RPM but also upon the torque of the driving aggregate.
Furthermore, it can be advantageous if a certain desired clutch torque is transmitted by the torque transmission system substantially at each point in time. It can thereby be expedient if the transmittable clutch torque follows the existing torque.
Such embodiment exhibits the advantage that the contact pressure of the torque transmission system need not be maintained permanently at the highest value. According to the teaching of prior art, a torque transmission system (such as a clutch) is acted upon by a multiple of the nominal engine torque.
In an automated torque transmission system, the following of the transmittable torque entails that the setting device or actor not only initiates the opening and closing processes during switching and starting but that the setting device selects the transmittable torque at each operating point to a value which corresponds at least substantially to the desired value.
In order that the setting device or actor need not be constantly active during follow-up, it may be expedient if the torque which can be transmitted by the torque transmission system is controlled with an overpressure and the overpressure lies within a narrow scatter band in relation to the desired value.
It can be expedient if the overpressure AM is dependent upon the operating point.
It can be particularly advantageous if the operating range is divided into partial ranges and the contact pressure and/or the maximum overpressure is fixed for each partial range.
In accordance with a further embodiment of the invention, it may be advantageous if the application of the contact pressure and/or of the overpressure and/or of the transmittable clutch torque is variable in time.
Similarly, according to the inventive concept, it may be advantageous if the transmittable clutch torque which is to be selected does not drop below a minimum value MMin. The minimum torque can depend upon the operating point and/or upon the momentary operating range and/or upon the time.
Furthermore, the torque follow-up can be carried out by a combination of a time-variable follow-up with a minimum value which follow-up is specific to the operating point.
According to the inventive concept, it can be advantageous if an operating point or the existing operating condition of a torque transmission system and/or of a combustion engine is ascertained on the basis of condition values determined or calculated from measurement signals, such as in dependency upon the engine RPM and the throttle valve angle, in dependency upon the engine RPM and the fuel throughput, in dependency upon the engine RPM and the inlet manifold underpressure, in dependency upon the engine RPM and the injection time or in dependency upon the temperature and/or friction value and/or slip and/or the load lever and/or the load lever gradient.
In a torque transmission system with a combustion engine mounted at the input side, it is of advantage if the input torque of the combustion engine can be determined from at least one of the condition values of the operating point, such as the engine RPM, throttle valve angle, fuel throughput, inlet manifold underpressure, injection time or temperature.
Still another embodiment of the method proposes that the torque MAN*KME which is applied at the input side of the torque transmission system is influenced and/or altered with a dependency taking into account the dynamics of the system, the dynamics of the system being adapted to be caused by the dynamic behavior as a result of the mass moment of inertia and/or free angles and/or damping elements.
It can be advantageous to provide means which purposefully restrict or influence the dynamics of the system.
Similarly, it can be advantageous if the dynamics of the system are realized to influence MAN*KME in a form corresponding to that of gradient restriction.
The gradient restriction can be realized as a limitation of a permissible increment.
Furthermore, it can be advantageous if the gradient restriction is realized in that the time-dependent change and/or the time-dependent increased intensity of a signal is compared with the maximum permitted slope or slope function and, when the maximum permissible increment is exceeded, the signal is replaced with a substitute signal which is incremented with a previously defined slope.
Furthermore, it can be advantageous if the influencing or restriction of the dynamics of the system is set up according to the principle of a timely dynamic and/or variable filter wherein the characteristic time constants and/or amplifications are time variable and/or dependent upon the operating point.
Advantageously, the dynamics of the system are taken into account and/or processed with a PT1 filter.
It can likewise be advantageous if the dynamics of the system are characterized by a maximum restriction wherein, when a certain threshold value is exceeded, the desired value is represented by the threshold value and, consequently, the desired value does not exceed a maximum value which is represented by the threshold value.
Furthermore, it can be advantageous to connect in series at least two means for controlling the system, such as a gradient restriction and a filter stage.
It can likewise be advantageous to connect in parallel at least two means for influencing the dynamics of the system, such as a gradient restriction and a filter.
It is particularly advantageous if the dynamics of the combustion engine and the dynamics of the secondary consumers which cause a load distribution are taken into account when determining the driving torque MAN. In such instances, it is especially advantageous if the mass moments of inertia of the utilized flywheel masses and/or elements are resorted to in order to take into account the dynamics of the combustion engine.
It can likewise be advantageous if the injection behavior of the combustion engine is relied upon and/or forms the basis for the consideration of the dynamics of the combustion engine.
It is likewise within the scope of the controlling method according to the invention to compensate for deviations from the ideal state long-term by taking into consideration the secondary consumers and/or the correction and/or the compensation for disturbances and/or sources of disturbances.
It can be advantageous if the torque being applied at the input side of the torque transmission system is detected and/or calculated as a difference between the engine torque Mmot and the sum of the torques taken up or branched off by the secondary consumers. For example, the secondary consumers to be considered can include the climate control and/or the dynamo and/or the servo pumps and/or the steering aid pumps.
According to the inventive concept, it can be advantageous if system condition values, such as the engine RPM and the throttle valve angle, the engine RPM and the fuel throughput, the engine RPM and the inlet manifold underpressure, the engine RPM and the injection time, the engine RPM and the load lever are used to determine the value of the engine torque Mmot.
Furthermore, it can be advantageous if system condition values are relied upon to ascertain the engine torque Mmot from a characteristic field of the engine. Analogously, it can be advantageous if system condition values are used to determine the engine torque Mmot and the engine torque is determined through the solution of at least one equation or an equation system. The solution of the equation or the equation system can be carried out numerically and/or can be ascertained from the characteristic field data.
Furthermore, it can be advantageous if the torque takeup resp. the load distribution of the secondary consumers is determined from measured values, such as voltage and/or current measured values of the dynamo and/or switch-on signals of the relevant secondary consumers and/or other signals indicating the operating condition of the secondary consumers.
Furthermore, it can be advantageous if the torque takeup of the secondary consumers is determined by means of measured values from the characteristic fields of the relevant secondary consumers. Likewise, the torque takeup of the secondary consumers can be determined by solving at least one equation or an equation system.
According to the inventive concept, it can be expedient if the corrected transmittable clutch torque can be determined according to the torque equation
MKSoll=KME*(MANxe2x88x92MKorr)+MSicher
and the correction torque MKorr is obtained from a correction value which is dependent upon the sum of torques taken up or branched off by the secondary aggregates.
Furthermore, it can be advantageous if a correction is carried out for disturbances or breakdowns which influence measurable system input values.
It can be particularly advantageous for the novel method if measurable disturbance factors are detected and/or identified and are at least partially compensated for and/or corrected through a parameter adaption and/or a system adaption. Furthermore, it can be advantageous if one utilizes measurable system input values in order to identify disturbance or breakdown values and/or to correct and/or to compensate at least partially for such values through parameter adaption and/or system adaption.
In order to identify a disturbance value and/or to correct the same by means of a parameter adaption and/or system adaption and/or to compensate for the same, at least in part, it is possible to use as parameters certain system input values such as for example temperatures, RPM, friction value and/or slip.
It can be particularly advantageous for the method if a compensation and/or correction of measurable disturbance factors is carried out through adaption of the characteristic field of the engine.
In such instances, it may very well be the case that one observes or registers a disturbance or breakdown value which need not be causally connected with the characteristic field of the engine but a correction of such disturbance value through an adaption of the characteristic field of the engine can be advantageous. In such instance, the cause of the disturbance is not corrected or compensated for.
Furthermore, it can be of advantage if a correction field of characteristic lines is established on the basis of a comparison between the desired clutch torque and the actual clutch torque, and a correction value is or can be ascertained for each operating point; such correction value is linked, additively and/or multiplicatively, with the value of the engine torque from the characteristic field of the engine.
Furthermore, it can be particularly expedient if, in view of a deviation detected at an operating point between the desired value and the actual value, analyses and/or undertakings are introduced in order to calculate and/or establish deviations and/or correction values at other operating points of the entire operating range.
Furthermore, it can be advantageous if, in the light of a deviation detected at an operating point, one introduces analyses and/or measures in order to calculate or establish deviations and/or correction values at other operating points of a limited operating range. As concerns the method, it can be of advantage if the limited operating ranges are set up in dependency upon the characteristic field.
Advantageously, an embodiment of the invention can be characterized in that the analyses and/or undertakings for the determination and/or calculation of deviations and correction values at the additional operating points take into account the entire operating range or a restricted operating range.
Furthermore, it can be advantageous if the analyses and/or undertakings for the calculation of deviations and/or correction values at the further operating points embrace only partial areas around the actual operating point. It can be particularly advantageous if the analyses and/or undertakings for the determination and/or calculation of deviations and/or correction values are carried out at the further operating points in such a way that weighting factors evaluate or emphasize different portions of the entire operating range in different ways.
It can be advantageous if the weighting factors are selected and/or calculated as a function of the operating point. It can likewise be advantageous if the weighting factors can depend upon the type of the disturbance or breakdown value and/or upon the cause of the breakdown.
Furthermore, it can be particularly advantageous if, upon completed determination of the correction value and/or subsequent to weighting of the characteristic correction field, a time behavior is impressed upon the correction value. For example, such time behavior may take into account the dynamic behavior of the system.
It can be advantageous if the time behavior is determined through a pulse frequency, a scanning of the correction value and/or if the time behavior is determined by at least one digital and/or analog filter.
It can be particularly advantageous in an embodiment of the invention if the time behavior is varied for different breakdown values and/or different breakdown sources, namely in the event of using a relevant filter the parameters of the filter are set in dependency upon the nature and the manner of action of the breakdown source. Thus, the time constants and amplifications of the filters conform to the respective breakdown sources in order to guarantee an at least substantially optimal adaption.
It can be advantageous if the time behavior is selected in dependency upon the value of the corrections. It can be particularly advantageous if the driving torque is adapted with an adaption method with greater or smaller time constant than the time constant of the adaption method of the clutch torque. It is advantageous if the time constant is within a range of between 1 second and 500 seconds, but preferably within a range of between 10 seconds and 60 seconds and most preferably within a range of between 20 seconds and 40 seconds.
In accordance with a further embodiment, it can be expedient if the time constant is dependent upon the operating point and/or if the time constant is selected and/or ascertained differently for different operating ranges. Furthermore, it can be of advantage if a compensation for and/or correction of measurable breakdown values is carried out through adaption of the inverse transfer function of the transmission unit with setting member.
A further advantageous embodiment of the method provides that indirectly measurable breakdown values, such as especially the aging and/or straying of individual component parts of the torque transmission system are detected in that some characteristic values of the torque transmission system are monitored and the actually disturbed parameters are detected and corrected in dependency upon such monitoring and/or virtual breakdown sources can be put to use in the form of program modules in order to correct and/or compensate for the influence of the breakdown values.
Furthermore, it can be advantageous if disturbances from non-measurable influence values, the straying of individual component parts and/or the aging are detected and/or compensated for through deviations from condition values of the system. Furthermore, it can be advantageous if disturbances or breakdowns, such as straying or aging or other non-measurable influence values, are not detected from measurable input values but are recognized only by observing reactions of the system.
It can likewise be advantageous if the deviations from system condition values or condition values and/or observations of system reactions are measured directly and/or calculated from other measured values in a method model. It can likewise be advantageous to carry out the detection of deviations from calculated method models by resorting to characteristic reference fields and/or unequivocal characteristic reference values of the system.
Another advantageous further development of the invention provides that, for the correction and/or for the compensation of a detected disturbance or breakdown from non-measurable input values a breakdown source be localized and/or a breakdown source be fixed and the deviations at these breakdown sources be corrected and/or compensated for. Furthermore, it can be expedient if, for the correction of and/or for the compensation for a detected breakdown, one fixes a fictional breakdown source which need not have a causal connection with the breakdown and at which the detected deviation is corrected.
Advantageously, the fixed breakdown source can be an actually existing function block and/or the fixed breakdown source can constitute a virtual breakdown model whilst preserving the correcting action.
According to a further development of the invention, the timely progress of the actual clutch torque is monitored and analyzed to ascertain whether conclusions regarding the type of error and/or the detection of the breakdown source and/or the localization of the breakdown source can be arrived at.
Furthermore, it can be advantageous to permanently carry out the adaptive correction of the breakdown value.
A further advantageous embodiment proposes that the adaptive correction of the breakdown values be carried out only at certain operating points and/or within certain operating ranges and/or time ranges.
Furthermore, it can be advantageous if the adaption can be active when the control is inactive. In this context, xe2x80x9cinactivexe2x80x9d can denote that the control does not engage in or cause or carry out any activity of the setting member since, for example, an operating range is selected or actually exists in which a torque follow-up is not carried out but, instead, a stationary value is set. In this operating range, one can carry out an adaption of the parameter without carrying out an active control.
Furthermore, it can be advantageous if the adaption is not carried out within special operational ranges, especially in the event of pronounced acceleration.
It can be expedient if, within the operating ranges of inactive adaption, one utilizes correction values of the setting values which were detected within the previously determined operating ranges of active adaption. Furthermore, for such procedure, it may be expedient if the previously detected values for an adaption are stored in an intermediate memory and can be addressed in situations of a deactivated adaption.
In a further embodiment of the invention, it may be expedient if, within the operating ranges of inactive adaption, one applies correction values of the breakdown values which can be extrapolated with active adaption from correction values in previously detected operating ranges.
In accordance with a further method according to the invention, it can be expedient if one adopts virtual breakdown models and/or virtual breakdown values for the areas of the engine torque and/or for the area of the net engine torque, after taking into account the secondary consumers, and/or for the desired clutch torque.
Furthermore, it can be advantageous if one introduces and/or employs the inverse transfer function of the transmitting unit with setting member as a virtual breakdown source.
Furthermore, it can be expedient if the characteristic field of the engine is used as the virtual breakdown source.
It is particularly advantageous if virtual breakdown sources are used to define breakdown values whose original causes cannot be localized, such as for example straying in the region of manufacturing tolerances of the individual component parts.
A further novel concept of the invention relates to a method of controlling a torque transmission system with or without load distribution wherein the clutch torque adapted to be transmitted from an input side to an output side of the torque transmission system is used as a control value and such control value is put to use by means of a setting member to which is assigned a setting value which is functionally dependent upon the transmittable clutch torque, so that the transmittable clutch torque always lies within a predetermined tolerance band around the slip limit, and the slip limit is reached at the exact time when the action of the torque developing at the input side exceeds that clutch torque which can be transmitted by the torque transmitting parts.
Furthermore, it can be advantageous if the setting member is assigned as a setting value a value which corresponds to the clutch torque adapted to be transmitted between the torque transmitting parts of the torque transmission system.
A further expedient development of the invention proposes that the setting value be determined in dependency upon a transmittable clutch torque and that, in order to calculate such transmittable clutch torque, one establishes a difference between the value of the driving torque and a correction value wherein the correction value is increased or reduced in dependency upon at least one condition value of the torque transmission system.
Furthermore, it can be expedient if the correction value is determined in dependency upon a differential RPM between an input RPM and an output RPM, designated slip RPM, the correction value being increased as long as the slip RPM is below a predetermined threshold slip value and the correction value being reduced as long as the slip RPM is above such or another predetermined threshold slip value.
Furthermore, it can be of advantage if the correction values are increased incrementally as long as the slip RPM is below the one threshold slip value and the correction value is reduced stepwise as long as the slip RPM is above the one or another threshold slip value. Stopping phases of adjustable length are provided between the relevant stages and, during each stopping stage, the correction value is kept constant at a value set at the outset of each stopping stage.
Furthermore, it can be advantageous if the times during which the input RPM exceeds the output RPM by a defined slip RPM are recognized as the slip phase and at the end of each slip phase the correction value is set again to a definite value.
An advantageous embodiment of the invention proposes that the times during which the input RPM exceeds the output RPM by a definite slip RPM be recognized as slip phases, and that the relevant correction value at which the slip RPM assumes its maximum value be stored in an intermediate memory and at the end of a slip phase the actual correction value be again replaced by the stored correction value.
It can likewise be advantageous if the correction value be kept constant at its relevant value for a fixable interval of time at the end of each slip phase. According to another embodiment of the invention, it can be advantageous if the setting member is assigned a preset value in dependency upon a characteristic field or a characteristic line which embraces the area of all transmissible clutch torques or has at least one partial area within which only one preset value is allocated for the setting member for all transmissible clutch torques.
Furthermore, it can be advantageous that, in order to calculate the transmissible clutch torque, one forms a difference between an input torque value and the correction value, and this difference is increased by a torque value which is dependent upon slip.
According to a further embodiment of the invention, it may be of advantage if the rise of the actual clutch torque is restricted in the form of a gradient restriction in that the relevant actual value of the transmissible clutch torque is compared with a comparison torque value which consists of a previously detected transmissible clutch torque value and an additive fixable limiting value and that, in dependency upon such comparison, the smaller torque value is assigned to the setting member as the new preset value.
It can be particularly advantageous if several condition values, such as for example the engine RPM, throttle valve angle and/or suction intake pressure, are ascertained from a combustion engine mounted at the input side of the torque transmission system and the input torque of the combustion engine is detected from these condition values by means of stored characteristic lines or characteristic line fields. Furthermore, the invention proposes that eventual branchings of output between the drive and the torque transmission system be monitored at least partially or at least temporarily and the thus obtained measured values be used to calculate the input torque actually arising at the input side of the torque transmission system.
It can be advantageous if each time a part of the input torque corresponding to a proportion factor be used to calculate the transmissible clutch torque and if such proportion factor is determined each time from the stored characteristic line fields or characteristic lines.
Furthermore, it can be expedient if, with torque transmission systems without load distribution, a load distribution is reconstructed through a slave control program.
According to the inventive concept, it can be advantageous if measurable breakdown values, such as in particular temperatures and/or RPM, are detected and are compensated for at least partially through a parameter adaption and/or through a system adaption.
An expedient further development proposes that indirectly measurable breakdown values of the control method, such as in particular aging and/or straying of individual component parts of the torque transmission system, be detected by monitoring some condition values of the torque transmission system and, in dependency upon such monitoring, the actually affected parameters are recognized and corrected and/or virtual breakdown sources which can be switched on in the form of program modules are used in order to correct and/or compensate for the influence of the breakdown values.
Furthermore, it can be advantageous if a first engagement of the clutch is made possible only subsequent to checking of the authority of the user.
It can likewise be advantageous if a display, such as a user display, is controlled in dependency upon the status of the control method in such a way that a switching recommendation is given for the user. This switching recommendation can be carried out through the display in an optical manner or, alternatively, in an acoustic manner.
It can also be advantageous if phases of idleness, particularly of a vehicle, are recognized by monitoring significant operating values, such as accelerator pedal and/or gear linkage position and/or tacho RPM and, upon elapse of a defined time period, the driving unit is arrested and restarted when necessary.
Furthermore, it can be advantageous if operating phases of the torque transmission system with minimal or without load takeoff are recognized as freewheel phases and if the clutch is disengaged during such freewheel phases and is reengaged at the end of the freewheel phase. The end of the freewheel phase can take place or can be recognized, for example, through a detected change of the position of the load lever and/or of the load lever gradient.
According to a further embodiment of the invention, an antiblocking system can be assisted by applying the control method in such a way that, when the ABS system is active, the clutch is completely disengaged.
Furthermore, it can be advantageous if the setting member is controlled within certain operating ranges after actuation of the antislip control.
The invention not only relates to the aforedescribed method of controlling a torque transmission system but also relates especially to a torque transmission system for the transmission of torque from an input side to an output side wherein an internal combustion engine, such as a motor, is disposed at the input side and a gearbox is disposed at the output side and the torque transmission system has a clutch, a setting member and a control device.
Furthermore, the invention relates to a torque transmission system which can be controlled by means of the method described above and serves to transmit torque from an input side to an output side, wherein the output of the torque transmission system is connected in the power flow of a driving unit, such as a combustion engine, and a variable-transmission device, such as a gearbox, is installed in the power flow at the upstream or at the downstream side, and the torque transmission system comprises or contains a clutch and/or a torque converter with lockup clutch and/or a starting clutch and/or a turning set clutch and/or a safety clutch for limiting the transmissible torque, a setting member and a control device.
According to the inventive concept, particularly advantageous if the clutch is a self-adjusting or self resetting clutch.
It can be equally advantageous if the clutch automatically adjusts or compensates for wear, for example, upon the friction linings.
According to the inventive concept, it can be of advantage in actual practice of the invention if, in order to transmit the torque from an input side to an output side, the torque transmission system have a clutch, a setting member and a control unit wherein the clutch is operatively connected with the setting member through a hydraulic conduit which contains a slave clutch cylinder and the setting member is actuated by the control unit.
A further advantage resides in the utilization of a setting member having an electric motor which acts through an eccentric upon a hydraulic master cylinder which is attached to the hydraulic conduit which, in turn, is connected to the clutch, a clutch path sensor being mounted in the housing of the setting member.
In order to achieve a compact and flexible solution for the arrangement of the device according to the invention, it is advantageous if the electric motor, the eccentric, the master cylinder, the clutch path sensor and the required control and load electronics are mounted in the housing of the setting member.
It can likewise be of advantage if the axes of the electric motor and of the master cylinder are mounted to extend in parallelism with each other. It is particularly advantageous if the axes of the electric motor and of the master cylinder are mounted to extend in parallelism with each other in two different planes and are operatively connected to each other by the eccentric.
It can furthermore be of advantage if the axis of the electric motor extends in parallelism with a plane which is formed essentially by the board of the control and output electronics.
According to a further development of the novel torque transmission system, the mode of operation of the transmission system can be optimized by mounting a spring concentrically with the axis of the master cylinder in the housing for the setting member.
Furthermore, it can be advantageous if a spring is mounted in the housing of the master cylinder concentrically with the axis of the master cylinder.
It can be advantageous for the functioning of the apparatus according to the invention if a characteristic curve of the spring is selected in such a way that the maximum force to be applied by the electric motor to engage and disengage the clutch is approximately the same in the pull and push directions.
Furthermore, it can be advantageous if the characteristic curve of the spring is designed in such a way that the resulting progress of the forces acting upon the clutch is linearized during disengagement and engagement of the clutch. According to a further development, the power requirement and thus the size of the electric motor is minimized. Those forces which are required for the disengagement of the clutch are decisive for the dimensioning of the electric motor to be used since a greater force is needed for the disengagement than for the engagement of the clutch because the force of the spring assists the disengagement and, therefore, one can use a weaker electric motor.
By using a spring within the master cylinder piston, no additional space is required for the spring.
Furthermore, it can be of advantage if the electric motor having a motor output shaft acts upon a segment wheel through a worm and the segment wheel carries a crank which is operatively connected with the piston of the master cylinder by a piston rod in such a way that it is possible to transmit pushing and pulling forces.
It can likewise be of advantage if the worm and the segment wheel constitute a self-locking transmission.
The invention does not, however, relate only to the aforedescribed method of controlling a torque transmission system and to the torque transmission system itself, but also encompasses a monitoring method for a torque transmission system with a manually actuatable gearbox, wherein relevant gear lever positions and an input torque of a driving unit at the input side are detected with a sensor system and at least one corresponding gear lever signal and at least one comparison signal are recorded and different possible characteristics of the progress of these signals, such as for example a difference, are recognized and identified as the switching intention and a switching intention signal is then transmitted to a clutch operating system at the output side.
As concerns the inventive concept, it can be advantageous if at least one progress of the gear lever signal is evaluated to detect the selected gear and such information is used to identify a switching intention.
The monitoring method ascertains the gear which is engaged at that time, and such information can be used to determine the comparison signal.
In this manner, one provides a method with which an eventual switching intention of the user is recognized at a high speed and in a highly reliable manner without it being necessary to use a specific sensor. A predominantly automated torque transmission system requires early information regarding a possible switching intention in order to disengage the clutch in good time.
It can be advantageous if a gear lever signal and a comparison signal are evaluated in such a way that intersecting points of these signal paths are detected and then a switching intention signal is transmitted to the clutch operating system at the output side. If, in order to detect the switching intention, only two signal paths are investigated or evaluated for intersecting points, there is no longer any need for expensive software or hardware.
According to the inventive concept, it can be advantageous if, with the switching gearbox, a selection path is differentiated between the switching lanes and a switching path within the switching lanes. The switching path and/or the selection path can be monitored in order to determine the relevant gear lever position.
Also, there is no need for additional sensor systems for the generation of the comparison signal since, as a rule, the single input value (namely the input torque) can already be determined. Since the comparison signal is formed from a filter signal wherein the filter signal is intensified and/or weakened by a constant value and an offset signal, it is practically ensured that the gear lever signal and the comparison signal intersect only if a switching intention actually exists.
In accordance with an advantageous further development, the existence of a switching intention is detected during monitoring of the two signal paths of the gear lever signal and the comparison signal if an intersection point is detected and, at such time, the switching intention is verified by means of a switching intention counter. With the claimed switching intention counter, one ensures that a definite interval of time elapses between the realization of the switching intention and the transmission of the switching intention signal, and such interval of time suffices to ascertain whether a switching operation is actually initiated. In this manner, the torque transmission system is effectively protected against an unintentional release.
The gear lever signal is filtered with an adjustable time delay in order to generate a filter signal.
It can be particularly advantageous if the gear lever signal can be processed to form the filter signal with a PT1 characteristic.
Furthermore, it can be advantageous if the gear lever signal is monitored and a change of the switching path within a defined portion of the gear lever path is evaluated within a fixable measuring period in such a way that a switching intention signal is transmitted to devices at the output side when a fixable switching path change threshold is not reached.
The gear lever signal, which is used to ascertain the existence of a switching intention, which in turn is passed on, can be tuned by means of individually adjustable filters, which are universally usable through filter parameters, in such a way that a wide variety of torque transmission systems can be monitored by resorting to the same method. It is advantageous if the measuring period is fixed in such a way that it is always clearly greater than a half vibration period resp. vibration amplitude of the gear lever which is not actuated during operation of the vehicle.
It can be expedient if the defined portion of the gear lever path is outside of the gear lever path areas within which the non-operated gear lever moves when the vehicle is in operation.
In order to practice the method according to the invention, it is necessary as a rule to average the gear lever vibration periods. In this manner, the duration of the measuring period can be fixed in dependency upon the formation of average value of the gear lever vibration period.
In accordance with a further development, one can ascertain whether the gear lever vibrates freely during operation of the vehicle or has a different vibration behavior, especially when a hand is placed thereon. The mean value formation to determine the length of the measuring periods is carried out in dependency upon the results of such monitoring.
According to a further development of the invention, it can be advantageous if the direction of movement of the gear lever is detected and when such direction of movement is reversed, a control signal is transmitted to the switching intention counter and/or an already transmitted switching intention signal is rescinded.
In this manner, the direction of movement of the gear lever is additionally observed and a reversal of such direction of movement entails a rescinding of a switching intention signal which would otherwise be transmitted as a result of vibration of the gear lever.
Furthermore, it can be advantageous if the constant value for the generation of the comparison signal is selected in dependency upon the typical operating vibration amplitude of the non-operated gear lever of the torque transmission system.
It can likewise be advantageous if the delay time with which the filter signal is generated is caused to conform to the vibration frequency of the gear lever which is not actuated during operation of the vehicle.
In accordance with the inventive concept, it can be particularly advantageous for a control method if the driving load is monitored and, on exceeding a fixable driving load, a control signal is transmitted to the switching intention counter. In this manner, one can prevent that, in the event of an increased torque at the engine side, the clutch is unintentionally disengaged or engaged. It can likewise be advantageous if the offset signal is applied in dependency upon the relevant throttle valve angle in a combustion engine which is used as the driving unit.
In accordance with the inventive concept, it is expedient if the switching or selection path of the gear lever is ascertained by a potentiometer. It can likewise be advantageous if the switching and/or selection path of the gear lever is ascertained by a potentiometer in such a way that the gear setting can be recognized by the potentiometer.
However, the invention does not relate only to the aforediscussed method of controlling a torque transmission system but also encompasses those processes for controlling a torque transmission system having a device for controlling the torque transmission system, the torque transmission system is mounted at the output side in the power flow of a driving unit and at the input and/or output side in the power flow of a variable transmission device, the variable transmission device being provided with endless flexible means which transmit torque from a first means to a second means, the first means being operatively connected with the input shaft of a gearbox and the second means being operatively connected with an output shaft of the gearbox, the endless flexible means is in frictional contact with the first and the second means through contact pressure or tensioning and the contact pressure or tensioning of the endless flexible means being controlled in dependency upon the operating point, characterized in that the torque transmission system is started with follow-up torque, namely with a transmissible torque which is dimensioned at each operating point in such a way that the endless flexible means of the variable transmission device does not begin to slip. This means that the slip limit of the torque transmission system is controlled at each operating point so that the slip limit of the endless flexible means is always greater and if the applied torque is excessive, the torque transmission system always begins to slip before the endless flexible means slips.
Furthermore, it can be advantageous if the contact pressure and/or tensioning of the endless flexible means is determined and applied at each operating point in dependency upon the applied engine torque and/or the load distribution or branching off regarding the secondary consumers and an additional safety tolerance and the transmissible torque of the torque transmission system is controlled in dependency upon the operating point and the torque transmissible by the torque transmission system entails, in the event of torque fluctuations, slippage of the torque transmission system before the slip limit of the endless flexible means is reached.
It is particularly expedient if the slip limit of the torque transmission system at each operating point is lower than the slip limit of the endless flexible means of the variable transmission device.
In accordance with the novel concept, it can be of additional advantage if the torque transmission system with its slip limit dependent upon the operating point isolates and/or damps torque fluctuations and torque surges at the input side and/or at the output side and protects the endless flexible means against slip. Thus, the endless flexible means is protected against slippage because the slippage under the above outlined circumstances could lead to destruction of the endless flexible means and thus to a breakdown of the gearbox.
According to the inventive concept, it is expedient to control the contact pressure or the tensioning of the endless flexible means in dependency upon the operating point and, in addition to the applied torque, to take into account a safe reserve which can be caused to approximate and/or to conform to the transmissible torque through the selection of the transmissible torque of the torque transmission system. The adaptation of safety torque can be carried out in this case in such a way that the selected safety reserve can be less than in accordance with prior art proposals.
It can be particularly advantageous if the safety reserve of the contact pressure or tensioning is as low as possible as a result of protection of the torque transmission system against slip.
It is particularly expedient if the torque transmission system slips or slides only briefly in the event of torque surges. It is thus possible to isolate or damp or filter torque surges at the input side or at the output side; such surges may occur in extreme driving situations and could damage or destroy the endless flexible means.
The invention relates not only to the aforedescribed method but also to an apparatus, such as a variable transmission device, which is controlled in accordance with the aforementioned method and wherein the variable transmission device can be an infinitely adjustable gearbox. It may be especially advantageous if the variable transmission device is an infinitely adjustable cone pulley belt contact gearbox. It can also be particularly advantageous if the torque transmission system which is part of the apparatus is a friction clutch or a converter lockup clutch or a turning set clutch or a safety clutch. The clutch can be a dry clutch or a wet clutch. Furthermore, it may be expedient to provide a setting member which controls the transmissible torque and is controlled electrically and/or hydraulically and/or mechanically and/or pneumatically, or the actuation of the setting member is effected by a combination of these undertakings.
The invention does not relate only to the aforedescribed methods but especially also to an apparatus with at least one sensor for the detection of the effective gear ratio or the engaged gear of a gearbox, a central computer unit being provided to process the sensor signals and to calculate the gearbox input speed. For such calculation, it is further necessary to take into consideration the transmission ratios, such as the transmission ratios of the differential.
It can be of advantage if the ascertained rotational speeds of the wheels are averaged and the thus obtained averaged signal is utilized to ascertain or to calculate the gearbox input RPM by taking into consideration the transmissions in the power train and the transmission ratio of the gearbox.
It is of advantage if the rotational speed of the wheels is ascertained by utilizing one to four sensors, and is particularly advantageous if one employs 2 or 4 sensors.
The apparatus can be constructed in a particularly advantageous manner and way if the sensors which serve to detect the rotational speeds of the wheels are in signal transmitting connection with the antiblocking system or constitute component parts of an antiblocking system.
The invention will be explained in greater detail with reference to an embodiment in the vehicle industry.